From power plants to electronic devices, many devices are cooled using pipes containing a fluid to carry heat away.

However, due to factors such as the shape of the devices that are being cooled, some parts of the devices get hotter than others and the cooling system has to be ramped up to account for this.

During his recently completed PhD, Azizian came across a clue for technology that could help in such a situation.

He was studying heat transfer in nanofluids, which are metal or metal oxide nanoparticles dispersed in a fluid.

Azizian discovered that when such nanoparticles clump together, they transfer heat faster.

He then came up with the idea of using magnetite nanoparticles to develop a new way of cooling down hotspots.

Magnetic manipulation

Unlike normal-sized particles, nanoparticles do not settle out of fluid or cause corrosion of pipes.

Azizian reasoned that magnetic fields could be used to manipulate the magnetic nanoparticles in the cooling fluid, clumping them together on the inside surface of a cooling system pipe, to increase the rate of heat transfer.

While a visiting student at MIT, Azizian took the opportunity to test this idea.

He made up a fluid containing less than 1 per cent by volume magnetite nanoparticles and pumped it through a test cooling system. The nanofluid had the same heat transfer properties as water.

But when Azizian applied magnets to the outside of the pipe at different locations, nanoparticles clumped together on the inside surface of the pipe, and the rate of heat transfer increased by 300 per cent.

"It was very surprising," he says.

Azizian says the particles are probably increasing heat transfer by forming a solid chain for heat to flow to the outside of the cooling pipe.

He says a cooling system based on this technology could overcome limitations of current-day systems which rely on bigger pumps or features like fans, fins and grooves on pipe surfaces to overcome hotspots.

Not only do these measures increase cost and/or the size of the system, but they require the whole system to be designed to deal with hotspots.

"With this nanofluid system, you can design your system according to the normal situation and wherever you have hot spots you can apply these magnetic fields to increase heat transfer at that specific spot," says Azizian.

He says if electromagnets were used instead of permanent magnets, it also might be possible to control the rate of heat transfer by changing the strength of the magnetic field.

However, Azizian says much more work needs to be done to take the technology into the "real world" as there could be, for example, problems using magnetic fields near electrical devices or power plants.

"I think applications at this stage remain well in the future," he says.